DESCRIPTION: The undesired destruction of healthy cells by the immune system results in the loss of tissue function and complicates strategies to restore tissue function. The current standard therapy for autoimmune disease involves generalized immunosuppression, which is in most cases is not clinically efficacious and leads to numerous undesired side effects. Dr. Stephen Miller, (co-PI) pioneered an approach in which splenocytes were cross-linked with specific auto antigens, and their delivery to the spleen induced tolerance specifically to the auto antigen. This approach was recently adapted for a clinical trial in multiple sclerosis (MS) patients, and was the first-in-man study to report the induction antigen specific tolerance. However, the use of cellular carriers for tolerance induction in the clinical arena is challenging due to the considerable ex-vivo laboratory manipulation that is required, which is expensive, increases the number of donor cells needed and introduces further opportunity for technical error. Our long-term goal is to develop a particle-based platform that can be an off-the-shelf product for induction of tolerance to specific antigens to inhibit the specific undesired immune response while not altering the remaining elements of the immune response. We have demonstrated that antigen-loaded particles delivered intravenously can induce tolerance for the prevention and treatment of experimental autoimmune encephalomyelitis (EAE), the mouse model of MS. With the goal of moving this technology toward the clinic, we propose to extend these studies to address fundamental questions about the particle design and their mechanisms of action, and also critical questions regarding the ability to target the variety of antigens and cell populations underlying disease. Specific Aim 1 will investigate the particle design parameters and identify the cellular mechanisms by which particles injected intravenously are able to modulate inflammation and induce antigen specific tolerance. Our results suggest the liver as a critical site involved in tolerance induction from the particles, which distinguishes it from the previous work with antigen-coupled splenocytes. We propose to investigate the particle composition and size to distinguish i) the impact of the carrier on immune cell polarization, ii) te efficacy of antigen presentation, and iii) in vivo trafficking of the particles. Specific Aim 2 wil determine the cellular and molecular mechanisms by which Ag-PLG tolerance is induced and maintained in nave, activated, and memory T cells. We propose to test the ability to induce tolerance with particles encapsulating multiple peptides/proteins and to examine the separate and combined contributions of anergy and Tregs to the induction and maintenance of tolerance. Successful completion of these studies would identify particles that are novel, safe, efficient and clinically relevant tools to inhibit antigen-specific T-cells for therapy of autoimmune diseases. This innovative approach has far reaching implications for decreasing specific immune responses in applications such as autoimmune disease, rejection of transplanted cells, and allergies to food antigens or airborne particulates.